The Leviathan was once headed here in a search for a cure for the Epideme virus, but it never reached it's destination due to it's engines overloading, and all the crew were killed by Epideme as the ship froze.

Three million years later, the crew of Starbug also went to Delta VII for the same purpose in looking for an Epideme cure as Dave Lister had been infected. However, flying over the surface they found it had long been been fire-stormed into ashes due to an outbreak of the Epideme virus on Delta VII. Instead of curing Epideme, Delta VII had evidently succumbed to it much like the Leviathan. ("RD: Epideme")

Trivia

Given that it was clearly a viral research facility, and it was considered the destination for the hope of a cure for Epideme by at least two starships, it is possible that Delta VII was the origin of the Epideme virus.

The NaviComp of the Leviathan

The navicomp of the Leviathan is briefly seen in the episode, just as Lister stops the TNT detonation. This suggests that the home base of call of the Leviathan was a planet called "Theta 4". The same readout also suggests that it's destination Delta VII was once a blue world like Earth.